Cannabis may harm chance of successful treatment for cancer patients - study

Cannabis consumption by advanced cancer patients lightens symptoms and side effects, but may impair the success of immunotherapy.

cannabis background macro close up (photo credit: INGIMAGE)
cannabis background macro close up
(photo credit: INGIMAGE)
Cannabis, widely used by cancer patients to help deal with the symptoms and side effects of various treatments, may impair the chances of success of immunotherapy, a new study shows.
Immunotherapy, considered to be the most significant breakthrough in the field of cancer treatment in the last decade, is a method of treatment which uses the patient's immune system to detect and attack cancer cells more effectively.
The study, supported by the Israel Cancer Association (ICA), was led by Israeli researchers Dr. Idan Cohen and Prof. Gil Bar Sela from the Oncology Department at HaEmek Medical Center in Afula, and the Rappaport Faculty of Medicine at the Technion, together with Prof. Dedi Meiri from the Technion's Faculty of Biology.
"The Israel Cancer Association recognizes the importance of research in the field of cancer, and each year provides support and funding for dozens of leading studies selected by the association's research committee," according to ICA director-general Moshe Bar-Haim.
The study pointed out that while cannabis consumption reduced treatment-related side effects, a correlation was also found between cannabis use and the shortening of time until the disease worsened, along with a dramatic decrease in overall patient survival rates.
“There is a laboratory study that suggests that cannabis suppresses the components of the immune system that are activated by immunotherapy," noted Bar Sela, pointing out that, similar to cannabis, "steroids also suppress the immune system, so it is recommended not to start immunotherapy if you are taking moderate-dose or higher steroids regularly" and that "it may be worth giving a similar recommendation regarding cannabis as well."
"That is, if at the starting point of immunotherapy treatment, the body is under the influence of cannabis, the immune system is probably suppressed to some degree and the success of immunotherapy may be impaired," he added.
It is important to note that the current study is not without limitations given the small number of subjects – 102 patients with advanced cancer who started immunotherapy, of whom 68 did not consume cannabis and 34 did.
The study reinforces the results of a previous study conducted in 2014, also led by Bar Sela, showing that when patients were asked in retrospect if they used cannabis during the treatments, the results were similar.